I wanted to see how core.typed would deal with annotating some of my production Clojure code. After hitting an issue with protocols, and spending all of 5 minutes unable to fix it, my gen Y attention span kicked in and I lowered my goals. Instead I wrote a plain Clojure solution to Conway's Game of Life and then annotated it with core.typed. Then got a friend to re-write it in Scala. Then re-wrote it myself in Haskell.